Ecoboost Performance Forum

Ecoboost Performance => Troubleshooting, Maintenance, TSB Articles => Troubleshooting => Topic started by: Hopelessdj on May 04, 2021, 08:25:20 PM

Title: SHO low fuel pressure help
Post by: Hopelessdj on May 04, 2021, 08:25:20 PM
Ok so my car likes to drop pressure to around 7-9kpa at wot. I have a brand new hpfp and lpfp, 02 sensors, coils, plugs, blow off valves and intercooler pipes (had a boost leak too). 

The car doesn't drop pressure on my lower boost tune or stock tune. Only when running the "average" boost level tune from  gearhead. It should be able to run this tune just fine, it's nothing special. I don't have bigger turbos or xdi or anything crazy done to the car. Ortiz also couldn't finish tuning due to the pressure drops, we had to keep a lower boost tune.

When I had my boost leak, the tunes all held pressure perfect, cause I wasn't hitting that much boost. As soon as I hit like 15psi it'll drop and won't recover to anything above 10 or 11 kpa at wot.

Any ideas what to check next? Could this be the most my stock fuel system can handle or do I have a bad part I'm still chasing? I had assumed something must be wrong cause 2 tuners are telling me they normally run these levels just fine on cars with my kind of set up.

Also not sure if it's worth noting but the pressure dip worsened slightly after putting in new 02 sensors while chasing the problem. Tuner says he believes the sensors were going bad and asking for more fuel which made the pressure a little better. I find it odd that it would have gotten better pressure then but can't now tho
Title: Re: SHO low fuel pressure help
Post by: SHOdded on September 23, 2021, 02:47:13 PM
You did not mention what year your SHO is, that would be helpful.

Might have to look into a new FPCM. do you have a 3 bar map installed? check all the IAT and MAP sensors for oil fouling.  may have the intercooler blowing crud thru the throttle body into the intake.

any raw fuel smell or black smoke from the exhaust to indicate possibly leaking injector? are the fuel trims behaving until the point the issue begins?  i am assuming no knock issues since your tuners have not raised that possibility.

and of course, no codes?

any datalogs to share?
Title: Re: SHO low fuel pressure help
Post by: ridered74 on September 24, 2021, 11:13:01 AM
Maybe the fuel pressure sensor that is under the intake manifold? I've heard of a few people having to replace that. Don't remember what their symptoms were tho.
Title: Re: SHO low fuel pressure help
Post by: SHOdded on October 03, 2021, 06:50:35 AM
maybe a sticking wastegate or blowoff valve or even solenoid? usually see a loss of pressure rather than overboost, but you never know.  you said pressure held perfectly during the boost leak, so ...
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